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[2620:137:e000::1:20]) by mx.google.com with ESMTP id w28-20020a63af1c000000b004e299dbbec9si17926130pge.372.2023.02.01.19.24.31; Wed, 01 Feb 2023 19:24:47 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20210112 header.b=WhSUIlvP; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231681AbjBBDFD (ORCPT + 99 others); Wed, 1 Feb 2023 22:05:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44550 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231697AbjBBDEs (ORCPT ); Wed, 1 Feb 2023 22:04:48 -0500 Received: from mail-pl1-x64a.google.com (mail-pl1-x64a.google.com [IPv6:2607:f8b0:4864:20::64a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D5BCD1167C for ; Wed, 1 Feb 2023 19:04:44 -0800 (PST) Received: by mail-pl1-x64a.google.com with SMTP id x6-20020a1709029a4600b0019747acb19cso284637plv.5 for ; Wed, 01 Feb 2023 19:04:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:from:to:cc:subject:date:message-id :reply-to; bh=vmKwcK8nOOGhNuEtAlRRmLDd6QNY/0CCAJIdQUNwbyw=; b=WhSUIlvPiP3t5Byp86BE1TnJ8KqwB3vuESXiHWZr7bEaClkelX4feC4ncvGcBO0C+f a54h37SiNBF0GMyZYRdy7z0INyzyaC4eoVO9IriJLi1iQoCcTMZxh3YAhEdsCq9tCEZv GbtIgZg71Z6r5kUcVlmeT5vIlQcDWG5/bMTlUIowY8VRXv7OLNKhxy8hmT7E2yQ/S+p2 SmjZJEV+T6C88Ajwr5SC5w1dXM/4xD9k9CGkdF0dEdbOZ5zfCjo4qR/5J4QiOrstcj1N 28jCmuv1pplFDgdvqUwZbj74afDfGdeHMDLrjALR0ZBHK3LOGeyzYa94pp9p2IBmSPDV 27hg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=vmKwcK8nOOGhNuEtAlRRmLDd6QNY/0CCAJIdQUNwbyw=; b=ADu0viS2ufHyuYH62bGN5YzWc0Z0EGMwca9/qWBMFTqZvuWhzdjwAc6lC0NPESOqbj dsWOvVRwWV532s9PCQjQIUF9RU/V0gYJMA8NuOTPWHhwKGfKadxDUtKUg7bmWQNfowo3 PBz0IATpjV5mCYuKwEiLrMia8RenncZ+N/ASE0MILwQIImQGTHA6lobM/Ih+qIx8MnOd ZDyLA9+WaFkMhCE9PXGqd7M1OyGcb8WKTuw7Jeo8sv02wtdIKeo58rwqhsaH9FqHoY3c ZplHvxvKnHX7zwrq9s3O1pp0SXUh9r8/1FIlj+zIvt8VYsduB7Smui3qttz4+giriZqz VJeA== X-Gm-Message-State: AO0yUKUJpWxslg7P/izuTXulZnRYZx22JGoiQ/uq+QEmGwYLz+xq+PFc ibbvZ+6JehGZvzqQK1DflJ9CnfI2ZmI= X-Received: from avagin.kir.corp.google.com ([2620:0:1008:11:eee0:dc42:a911:8b59]) (user=avagin job=sendgmr) by 2002:a17:90a:8903:b0:226:9980:67f3 with SMTP id u3-20020a17090a890300b00226998067f3mr44814pjn.1.1675307083813; Wed, 01 Feb 2023 19:04:43 -0800 (PST) Date: Wed, 1 Feb 2023 19:04:27 -0800 In-Reply-To: <20230202030429.3304875-1-avagin@google.com> Mime-Version: 1.0 References: <20230202030429.3304875-1-avagin@google.com> X-Mailer: git-send-email 2.39.1.456.gfc5497dd1b-goog Message-ID: <20230202030429.3304875-5-avagin@google.com> Subject: [PATCH 4/6] seccomp: add the synchronous mode for seccomp_unotify From: Andrei Vagin To: Kees Cook , Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Christian Brauner , Chen Yu , avagin@gmail.com, Andrei Vagin , Andy Lutomirski , Dietmar Eggemann , Ingo Molnar , Juri Lelli , Peter Oskolkov , Tycho Andersen , Will Drewry , Vincent Guittot X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1756686843595429307?= X-GMAIL-MSGID: =?utf-8?q?1756688062828268685?= seccomp_unotify allows more privileged processes do actions on behalf of less privileged processes. In many cases, the workflow is fully synchronous. It means a target process triggers a system call and passes controls to a supervisor process that handles the system call and returns controls to the target process. In this context, "synchronous" means that only one process is running and another one is waiting. There is the WF_CURRENT_CPU flag that is used to advise the scheduler to move the wakee to the current CPU. For such synchronous workflows, it makes context switches a few times faster. Right now, each interaction takes 12µs. With this patch, it takes about 3µs. This change introduce the SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP flag that it used to enable the sync mode. Signed-off-by: Andrei Vagin --- include/uapi/linux/seccomp.h | 4 ++++ kernel/seccomp.c | 31 +++++++++++++++++++++++++++++-- 2 files changed, 33 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/seccomp.h b/include/uapi/linux/seccomp.h index 0fdc6ef02b94..dbfc9b37fcae 100644 --- a/include/uapi/linux/seccomp.h +++ b/include/uapi/linux/seccomp.h @@ -115,6 +115,8 @@ struct seccomp_notif_resp { __u32 flags; }; +#define SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP (1UL << 0) + /* valid flags for seccomp_notif_addfd */ #define SECCOMP_ADDFD_FLAG_SETFD (1UL << 0) /* Specify remote fd */ #define SECCOMP_ADDFD_FLAG_SEND (1UL << 1) /* Addfd and return it, atomically */ @@ -150,4 +152,6 @@ struct seccomp_notif_addfd { #define SECCOMP_IOCTL_NOTIF_ADDFD SECCOMP_IOW(3, \ struct seccomp_notif_addfd) +#define SECCOMP_IOCTL_NOTIF_SET_FLAGS SECCOMP_IOW(4, __u64) + #endif /* _UAPI_LINUX_SECCOMP_H */ diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 876022e9c88c..0a62d44f4898 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -143,9 +143,12 @@ struct seccomp_kaddfd { * filter->notify_lock. * @next_id: The id of the next request. * @notifications: A list of struct seccomp_knotif elements. + * @flags: A set of SECCOMP_USER_NOTIF_FD_* flags. */ + struct notification { atomic_t requests; + u32 flags; u64 next_id; struct list_head notifications; }; @@ -1117,7 +1120,10 @@ static int seccomp_do_user_notification(int this_syscall, INIT_LIST_HEAD(&n.addfd); atomic_add(1, &match->notif->requests); - wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM); + if (match->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP) + wake_up_poll_on_current_cpu(&match->wqh, EPOLLIN | EPOLLRDNORM); + else + wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM); /* * This is where we wait for a reply from userspace. @@ -1593,7 +1599,10 @@ static long seccomp_notify_send(struct seccomp_filter *filter, knotif->error = resp.error; knotif->val = resp.val; knotif->flags = resp.flags; - complete(&knotif->ready); + if (filter->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP) + complete_on_current_cpu(&knotif->ready); + else + complete(&knotif->ready); out: mutex_unlock(&filter->notify_lock); return ret; @@ -1623,6 +1632,22 @@ static long seccomp_notify_id_valid(struct seccomp_filter *filter, return ret; } +static long seccomp_notify_set_flags(struct seccomp_filter *filter, + unsigned long flags) +{ + long ret; + + if (flags & ~SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP) + return -EINVAL; + + ret = mutex_lock_interruptible(&filter->notify_lock); + if (ret < 0) + return ret; + filter->notif->flags = flags; + mutex_unlock(&filter->notify_lock); + return 0; +} + static long seccomp_notify_addfd(struct seccomp_filter *filter, struct seccomp_notif_addfd __user *uaddfd, unsigned int size) @@ -1752,6 +1777,8 @@ static long seccomp_notify_ioctl(struct file *file, unsigned int cmd, case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR: case SECCOMP_IOCTL_NOTIF_ID_VALID: return seccomp_notify_id_valid(filter, buf); + case SECCOMP_IOCTL_NOTIF_SET_FLAGS: + return seccomp_notify_set_flags(filter, arg); } /* Extensible Argument ioctls */